Bis(hydrocarbyl) vinylphosphonates are sluggish monomers which are difficult to homopolymerize and copolymerize. Generally, a certain amount of residual, unreacted, oily vinylphosphonate will be present when such polymerizations are attempted. Since the vinylphosphonate reagent is relatively expensive, this amount of unreacted phosphonate results in a rather expensive and undesired waste of starting material. A need therefore exists for a process which will drive the conversion rate higher and produce a final product which is substantially free of unreacted, residual bis (hydrocarbyl) vinylphosphonate.